The present invention relates to monitoring a high-speed serializer-deserializer (SerDes) link, and more particularly relates to monitoring high-speed serializer-deserializer (SerDes) link channels to acquire a channel's eye patterns or eye characteristics, and adjusting link adaptive equalization settings, if possible, to realize improved link operation.
System architectures such as Infiniband and PCI Express utilize high-speed serializer-deserializer (SerDes) links to transmit data packets across serial links. These architectures are migrating to SerDes links that support link speeds at single data rates (SDR), double data rates (DDR) and quad data rates (QDR). In doing so, each architecture defines and provides for link-training methods that enable the high-speed SerDes link to support transmitting data at the higher data rates. One such architecture, Infiniband, provides for link operation at such higher data rates.
The Infiniband specification, Vol. 2, Rel. 1.2, supports adaptive equalization to compensate for signal distortion within link channels operating at the higher data rates. The Infiniband specification, section 5.6.4, Link Training State Machine, defines the procedure to enable adaptive equalization in an Infiniband system. The specification defines a 2 ms period to negotiate each side of a link's capabilities to support the SDR, DDR and QDR speeds. Once the negotiation process is completed, the Infiniband specification defines a 100 ms period to allow the default, or any of the 16 other possible (possibly available) adaptive equalization settings to be implemented across the entire link width, i.e., all of the link channels.
This solution is limited, however, in that one setting is selected for the entire link width (i.e., all of the channels). Link widths can be 1, 4, 8 and 12 channels wide using Infiniband, and up to 16 channels wide for PCI express. In an ideal system, every channel would be uniform and the above-mentioned method would be fine. In reality, however, this is hardly the case. That is, each medium or channel has it own set of impedance characteristics and tolerances. The Link Training State Machine method does not take into the account the varying characteristics between each channel. By limiting each channel to one set of adaptive equalization settings, some of the channels will not work optimally at DDR/QDR speeds. For example, at DDR/QDR speeds, real-time operation may find that only 8 channels out of the 12 available channels are operating effectively, which would result in a significant performance degradation for the entire link.
What would be desirable, therefore, is a new structure and process that allows for each channel within a high-speed Infiniband or PCI Express architecture to be independently monitored for optimal or less than optimal channel operation, in particular, the channel's eye opening, or eye patterns. Based on its monitored or detected eye characteristics, or eye pattern, the channel's adaptive equalization setting can modified where necessary (and if possible) to adjust the eye opening in the channel for improved channel processing.